Fix some tests and exclude others from CRLF rewriting.

pkg/js_ast/test/printer_callback_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// Note: This test relies on LF line endings in the source file.
+
 // Test that JS printer callbacks occur when expected.
 
 library js_ast.printer.callback_test;
 
 import 'package:js_ast/js_ast.dart';
 import 'package:unittest/unittest.dart';
 
 enum TestMode {
   NONE,
   ENTER,
@@ skipping 137 matching lines @@
     if (offset < text.length) {
       sb.write(text.substring(offset));
     }
     return sb.toString();
   }
 }
 
 void main() {
   DATA.forEach(check);
 }